Mineralogy Midterm Prep Flashcards
what is a mineral
MINERAL is a naturally occurring inorganic solid with a definite chemical composition & an ordered crystalline structure
Idiochromatic
The color of the mineral seldom varies, and is diagnostic.
Allochromatic
Color varies due to impurities or viewing angle
Chromophores
Elements with strong pigmenting capabilities
zoning
While a mineral is growing, environmental changes occur which produce different “chemical zones”.
What colors emrald (beryl) and ruby (corrundum)
Cr+3
Frenkel Defect?
Negative ion missing from structure, creating a site which will attract and trap any free electron; ELECTRON COLOR CENTER (F-Center)
Amethyst Color?
Iron containing quartz is exposed to gamma radiation from potassium 40 decay. (ENERGY OXIDIZES Fe3+ to Fe4+)
Color of smokey quartz?
radiation damage (of AlO4 group)- Al substitution for Si
Color in blue calcite?
shearing stress followed by radiation
Color in Quartz variety Chrysoprase?
chlorite impurities or mixture of nickel minerals
Color in Milky Quartz?
water inclusions
Blue Quartz?
Rutile inclusions (Tio2)
Opalescense?
optical affect from light bouncing off of microscopic spheres of silica spheres
Mohs Hardness Scale
Talc, Gypsum, Calcite, Flourite, Apatite, Orthoclase, Quartz, Topaz, Corundum, Diamond
define pseudomorph
different atomic structure; same crystal form
define polymorph
same chemical composition; change in crystal form (ex: diamond- graphite)
X-Ray Diffraction (XRD) tells you…
atomic structure (structural fingerprint)
electron microscopy energy dispersive xray flourescence for…
chemical analysis (chemical fingerprint)
what is the coloring agent of sapphire
Fe3+
color is a result of…
absorption, our eye blends the transmitted colors into a single color
where do diamonds occur
occurs in mantle derived kimberlite pipes along with other high temp/ high pressure inerals (the pipe picks up diamonds which formed in the mantle and rapidly carries them to the surface)
top 2 counties for diamond production…
botswana, russian federation
Where are pink diamonds from?
argyle mine, australia
what is the coloring agent of yellow diamonds?
nitrogen impurities
how is sulfur formed?
- precipitates near volcanic vents from volcanic gasses
- secondarily by oxidation of sulfide minerals
- reduction of gypsum in sedimentary rocks
Most common ore source of metals from (XmSn) (theres 8)
Fe, Cu, Zn, Pb, Ni, Co, Hg, Mo
This mineral is aka peacock ore
Bornite- rich colors from tarnish when mineral is exposed to air. from assorted copper oxides. (tarnish is bluish)
This group of minerals is known as the colorful ones
sulfosalts (a mineral in which a semi-metallic element replaces the metals)
Difference in Chemical structure of arsenopyrite, realgar, and orpiment
Arseno- FeAsS, Realgar- AsS, Orpiment- As2S3
Ochers are…
coloring agents (reds, yellows, oranges, blues, greens)
Difference between Malachite and Azurite…
Malachite- Green, Azurite- Blue
Azurite paint…
changes to a sickly green as the copper oxidizes and hydrates
Hematite
Fe2O3
Magnetite
Fe3O4
Limonite
FeO(OH)
Oxidation State of iron in hematite?
Fe3+
Oxidation state of iron in magnetite?
Fe2+ and Fe3+
Oxidation state of iron in limonite?
Fe3+
Manganese (Mn) oxides are called…
pyrolusite (manganese dendrites)
Hydroxide crystal chemistry for micas?
OH- main anionic froup forming sheets with weak bonds between
Brucite Type of Micas
trioctahedral sheets (all octahedral cation sites are filled)
Gibbsite-type
dioctahedral sheets (only two of three octahedral sites are filled)
black tatoos…
magnetite crystals
brown tattoos…
ochre
red tattoos…
cinnabar, cadmium red
orange tattoos…
monoazo pigments
flesh tattoos…
ochres
yellow tattoos…
cadmium yellow
blue tattoos…
azurite, cobalt
green tattoos…
chromium oxide
violet tattoos…
manganese violet
Earths crust’s 8 main elements:
oxygen (47%), silicon (28), aluminum (8), iron (5), magnesium (2), calcium (3.5), sodium (3), potassium (2.5)
Silicates make up what percent of minerals in the earths crust
more than 90
of the silicates, what percent exist as quartz and feldspars
q-10, feld- 51
what type of silicate is quartz
tectosilicate (3D framework of linked silicon tetrahedra)
What is the inversion temperature for displacive transformations of quartz
573 c
reconstructive polymorphism…
big deal (diamond-graphite)
displacive polymorphism…
not big deal (kinking as temperature decreases)
what causes quartz visual strain effects?
kinking at lower temperatures
order of quartz reconstructive formations?
Low quartz- stishovite or coesite
pressure of stishovite and coesite?
high
temperature of tridymite and cristobalite
high
Feldspars are…
the most abundant mineral in the crust (containing 6 of the 8 most common elements)
3 End members of feldspar series?
Albite (Na), Anorthite (Ca), Orthoclase (K)
Alkali Feldspars…
Albite—Orthoclase
Plagioclase Feldspars…
Albite—Anorthite
Chemical Composition of Sanadine/Orthoclase/ Microcline
KAlSi3O8
Chemical Composition of Albite
NaAlSi3O8
Chemical Composition of Anorthite
CaAl2Si2O8
There are more solid solutions at…
higher temperatures
General Formula for Alkali Feldspars
(K,Na)AlSi3O8
Potassium Feldspar minerals are…
polymorphs (same chemistry but different structure)
why are the k-spars polymorphs?
atomic positions of Al3+ and Si4+
What do the names of feldspars reflect
realities of compositional gaps as a result of exsolution
what determins whether Al3+ ions are ordered or disordered?
temperature
The order of sanidine is…
most disordered (random Al/Si configurations)
The order of microcline is…
most ordered (Al and Si divied into particular locations)
The order of orthoclase is…
intermediate (in between the others)
High temperature =
disorder
Sanidine has what symmetry?
mirror plane symmetry
Al avoidance principle…
cooling and separation of the Al and Si atoms, becomming ordered as to prevent the Al atoms from occupying adjacent sites
Perthite
intergrowths of albite. Na rich masses in a matrix of K-rich feldspar
Antiperthite
K spar masses in a matrix of sodium rich feldspar
exsolution?
coming out of solid solution. solution separating into 2 compositional masses
what is anorthoclase?
an intimate and submicroscopic intermixture of plagioclase and an alkali feldspar
Why does anorthoclase form?
rock composition, temperature of crystallization and crystallization rate
displacive phase transition happens when…
the cation in the cavity site is too small the there is a collapse of the framework (making an anorthoclase)
oswald step rule is…
a spontaneous reaction will never move from a stable state to a metastable state
what is twinning?
an accident that can occur during crystal growth
alkali feldspar twinning
twin lamallae
Plagioclase feldspar series general formula?
(Na,Ca)(Al,Si)4O8
Coupled Substitution in Plagioclase feldspars?
Na+Si4+ = Ca2+Al3+ (must maintain electric neutrality) (AT LOWER TEMPERATURES SUBSTITUTION DOES NOT WORK)
members of Plagioclase diagram?
albite, oligoclase, andesine, labradorite, bytownite, anorthite
What happens in a move from albite to orthoclase
Substitute Al3+ for Si4+ and an additional Na+ or K+ is added
What happens in a move from albite to anorthite
substitute 2 Al3+ for Si4+ and this allows Ca2+ to be added
domains are?
subatomic orders
Feldspathoids?
Silica poor feldspars
What is not one if the three most abundant groups in the earths crust?
Amphiboles
High quartz which is formed in most magmatic granites is
Usually transformed to low quartz upon slow cooling below 573c
The term domains in the plagioclase Feldspats refers to
Discrete chemically unique zones at the atomic level
Anorthoclase is a species of feldspar that forms as a result of
Rapid cooling
Plagioclase feldspar polysynthethetic striatum a are due to
Twinning
Sanidine is an
Alkali feldspar
One if the most important geologic and or environmental factors that causes and or results in the formation if one or another of the alkali feldspar polymorphs is
Ordering of al3+ and si4+
Sanidine forms at BLANK and has BLANK symmetry
High temperature; monoclinic
What is no longer considered a mineral by the international mineralogical commission?
Hornblende
What is not considered a mineral?
Glass
What information CANNOT be gathered from zoning in a crystal?
Lemurian codes
Which mineral does not obtain it’s color from radiation?
Ruby
The concentric growth between malachite and azurite and the chemical zoning of watermelon tourmaline are a result of
Environmental changes in a dynamic system
Tenacity can be defined as
Resistance to deformation
Why is there such variation in the color if fluorite?
Color centers
As you decrease temperature, ex solution in feldapars
Begins
What type of spectroscopy was used to locate water on Mars
Reflectance spectroscopy
An example of two common minerals which are pseudo morphs with the first changing to the second
Pyrite and limonite
Stenos law states that
The internal angles of crystal faces will remain constant, regardless of outward appearance
Spectroscopy is the changes in how BLANK interacts with a mineral
Energy
Visible light perceived by the human eye lies between
400 and 700 nanometers
Pyrope-almandine (gore mountain garnet) has BLANK and BLANK have parting surfaces
No cleavage, does
Minerals that have had their crystal structure destroyed due to radiation are
Metamictix minerals
An example of a fiberpus mineral would be
Chrysotile
Braggs law gives a mathematical relationship between
Crystal lattice spacing, wavelength and refraction angle
Nephrite is a BLANK and a jadeite is a BLANK and both form at
Amphibole, pyroxene; high pressures
Traces of cr3+ colors which 2 minerals?
Ruby and emrald
Emrald is a variation is BLANK and is usually BLANK in color
Beryl; green
Saphire is colored by traces of
Fe3+
Color in minerals is a result of BLANK wavelengths of light and our eyes see the BLANK colors
Absorbed; transmitted
Emeralds from Columbia South America often contain inclusions if pyrite or graphite. These inclusions indicate
Different source areas- chigoe and Mizo
What color does quartz turn after being heat treated
Colorless
The shroedinger model of the atom differs from the Bohr model primarily by
Assigning probabilities to the positions of orbital electrons
The country with the worlds largest supplier of gem emerald is
Columbia
Marcasite refers to
A polymorph of pyrite and a white pyrite rich in arsenic
Hope diamonds unique blue color is due to races of
Boron
Most of the sulfur cap rock often encountered in gulf coast salt domes originated from
Oxidation of gypsum by bacteria
Eh ph diagrams can be used to asses the
Stability feilds of sulfides carbonates and oxides
Which of the following is not a reconstructive transformation
Low quartz to high quartZ
Ex solution processes provide an opportunity for geologists to learn
To apply geothermometry analysis to coexisting mineral pairs
The extent/ amount if mineralogical solid solution is typically more extensive at
Higher temperatures
Displacing transformations observed for some varieties of quartz are
often slow and metastable because of the energy required for the change
What is the term for the major crustal aluminum hydroxide mineral
Bauxite
High quartz which is formed in most magmatic granites is
Usually transformed to low quartz upon slow cooling below 573
The chemical compositions of coexisting fe ti spinels (especially ilmenite magnetite rutile) can be used to decipher
Geothermometry and gas (oxygen) character and behavior
The most common mineral making up the earths crust is
Quartz, especially in igneous and metamorphic rocks
Which is not one if the three most abundant elements in the earths crust?
Calcium
CaCO3 is formed…
by various marine organisms and isnt different from the calcium carbonate phase formed from precipitation from a solution of heated water
Calcium carbonated can form which 2 different minerals
calcite or aragonite (polymorphs)
Pressure distinctions between calcite vs aragonite?
aragonite is high pressure (orthorhombic) Calcite is low pressure (hexagonal)
aragonite is often in what form?
the form in which the mineral is first precipitated
how does sedimentary aragonite form?
metastabaly due to supersaturation
if pressure time and comp for pearl formation is essentially the same, why does one or the other carbonate polymorphs form?
organic template for nucleation-introduction to nucleation and growth processes
what is an organic template?
thee organic molecule provides a template for nucleation from solution
Dolomite is a
common carbonate mineral containing Mg and Ca
Calcite is equivalent to what
to a modified NaCl structure
What substitutions are made with calcite
similarly sized cations for Ca+2
Calcite cleavage?
twin planes parallel to the long dimension of the rhomb (bisect the acute angle)
Dolomite cleavage?
twin planes parallel both the long and short dimension of the rhomb (bisect both the acute and obtuse angles)
What are the layers of dolomite?
alternating ca and mg layers (takes extra energy and time to order)
what are the common substiutions made?
ca-mg-fe (-mn)
talc and magnesite association due to…
metamorphosed ultramafics
major groups of sulfates?
anhydrous (no water) hydrous (water)
main members of barite group?
barite (BaSO4), celestite-celestine (SrSO4), Anhydrite (CaSO4), Crocoite (PbCrO4)
white sands caused by what?
weathered mountains which contain gypsum rich limestone. gypsum is dissolved by rain and water caries it. wind carried and crushed by wind
uses for gypsum?
fertilizer, concrete additive before its poured
what is incomplete calcination
gypsum rock heated to 100-190 and loses 3/4 of its water (plaster of paris)
complete calcinaion?
at temperatures above 190c all water is removed (anhydrite)
what is phosphogypsum
major bi prodcut of phosphoric acid production
desulfogypsum is?
obtained from the desulfurization of combustion gases in coal burning power plants
apatite associations from yates uranium mine?
fluorite and dipside
what is phosphorite?
phosphate rich sedimentary rock
